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Message-Id: <1398889543-23671-6-git-send-email-hannes@cmpxchg.org>
Date: Wed, 30 Apr 2014 16:25:39 -0400
From: Johannes Weiner <hannes@...xchg.org>
To: linux-mm@...ck.org
Cc: Michal Hocko <mhocko@...e.cz>, Hugh Dickins <hughd@...gle.com>,
Tejun Heo <tj@...nel.org>, cgroups@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [patch 5/9] mm: memcontrol: use root_mem_cgroup res_counter
The root_mem_cgroup res_counter is never charged itself: there is no
limit at the root level anyway, and any statistics are generated on
demand by summing up the counters of all other cgroups. This was an
optimization to keep down costs on systems that don't create specific
cgroups, but with per-cpu charge caches the res_counter operations do
not even show up on in profiles anymore. Just remove it and simplify
the code.
Signed-off-by: Johannes Weiner <hannes@...xchg.org>
---
mm/memcontrol.c | 157 ++++++++++++++++++--------------------------------------
1 file changed, 49 insertions(+), 108 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 788be26103f9..34407d99262a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2595,9 +2595,8 @@ static int mem_cgroup_try_charge(struct mem_cgroup *memcg,
unsigned long nr_reclaimed;
unsigned long flags = 0;
unsigned long long size;
+ int ret = 0;
- if (mem_cgroup_is_root(memcg))
- goto done;
retry:
if (consume_stock(memcg, nr_pages))
goto done;
@@ -2677,13 +2676,15 @@ nomem:
if (!(gfp_mask & __GFP_NOFAIL))
return -ENOMEM;
bypass:
- return -EINTR;
+ memcg = root_mem_cgroup;
+ ret = -EINTR;
+ goto retry;
done_restock:
if (batch > nr_pages)
refill_stock(memcg, batch - nr_pages);
done:
- return 0;
+ return ret;
}
/**
@@ -2723,13 +2724,11 @@ static struct mem_cgroup *mem_cgroup_try_charge_mm(struct mm_struct *mm,
static void __mem_cgroup_cancel_charge(struct mem_cgroup *memcg,
unsigned int nr_pages)
{
- if (!mem_cgroup_is_root(memcg)) {
- unsigned long bytes = nr_pages * PAGE_SIZE;
+ unsigned long bytes = nr_pages * PAGE_SIZE;
- res_counter_uncharge(&memcg->res, bytes);
- if (do_swap_account)
- res_counter_uncharge(&memcg->memsw, bytes);
- }
+ res_counter_uncharge(&memcg->res, bytes);
+ if (do_swap_account)
+ res_counter_uncharge(&memcg->memsw, bytes);
}
/*
@@ -2741,9 +2740,6 @@ static void __mem_cgroup_cancel_local_charge(struct mem_cgroup *memcg,
{
unsigned long bytes = nr_pages * PAGE_SIZE;
- if (mem_cgroup_is_root(memcg))
- return;
-
res_counter_uncharge_until(&memcg->res, memcg->res.parent, bytes);
if (do_swap_account)
res_counter_uncharge_until(&memcg->memsw,
@@ -3925,9 +3921,13 @@ int mem_cgroup_charge_file(struct page *page, struct mm_struct *mm,
* Page cache insertions can happen without an actual mm
* context, e.g. during disk probing on boot.
*/
- if (unlikely(!mm))
+ if (unlikely(!mm)) {
memcg = root_mem_cgroup;
- else {
+ ret = mem_cgroup_try_charge(memcg, gfp_mask, 1, true);
+ VM_BUG_ON(ret == -EINTR);
+ if (ret)
+ return ret;
+ } else {
memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, 1, true);
if (!memcg)
return -ENOMEM;
@@ -4083,7 +4083,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype,
* replacement page, so leave it alone when phasing out the
* page that is unused after the migration.
*/
- if (!end_migration && !mem_cgroup_is_root(memcg))
+ if (!end_migration)
mem_cgroup_do_uncharge(memcg, nr_pages, ctype);
return memcg;
@@ -4216,8 +4216,7 @@ void mem_cgroup_uncharge_swap(swp_entry_t ent)
* We uncharge this because swap is freed.
* This memcg can be obsolete one. We avoid calling css_tryget
*/
- if (!mem_cgroup_is_root(memcg))
- res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
+ res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
mem_cgroup_swap_statistics(memcg, false);
css_put(&memcg->css);
}
@@ -4903,78 +4902,24 @@ out:
return retval;
}
-
-static unsigned long mem_cgroup_recursive_stat(struct mem_cgroup *memcg,
- enum mem_cgroup_stat_index idx)
-{
- struct mem_cgroup *iter;
- long val = 0;
-
- /* Per-cpu values can be negative, use a signed accumulator */
- for_each_mem_cgroup_tree(iter, memcg)
- val += mem_cgroup_read_stat(iter, idx);
-
- if (val < 0) /* race ? */
- val = 0;
- return val;
-}
-
-static inline u64 mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
-{
- u64 val;
-
- if (!mem_cgroup_is_root(memcg)) {
- if (!swap)
- return res_counter_read_u64(&memcg->res, RES_USAGE);
- else
- return res_counter_read_u64(&memcg->memsw, RES_USAGE);
- }
-
- /*
- * Transparent hugepages are still accounted for in MEM_CGROUP_STAT_RSS
- * as well as in MEM_CGROUP_STAT_RSS_HUGE.
- */
- val = mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_CACHE);
- val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_RSS);
-
- if (swap)
- val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_SWAP);
-
- return val << PAGE_SHIFT;
-}
-
static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
- struct cftype *cft)
+ struct cftype *cft)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
- u64 val;
- int name;
- enum res_type type;
-
- type = MEMFILE_TYPE(cft->private);
- name = MEMFILE_ATTR(cft->private);
+ enum res_type type = MEMFILE_TYPE(cft->private);
+ int name = MEMFILE_ATTR(cft->private);
switch (type) {
case _MEM:
- if (name == RES_USAGE)
- val = mem_cgroup_usage(memcg, false);
- else
- val = res_counter_read_u64(&memcg->res, name);
- break;
+ return res_counter_read_u64(&memcg->res, name);
case _MEMSWAP:
- if (name == RES_USAGE)
- val = mem_cgroup_usage(memcg, true);
- else
- val = res_counter_read_u64(&memcg->memsw, name);
- break;
+ return res_counter_read_u64(&memcg->memsw, name);
case _KMEM:
- val = res_counter_read_u64(&memcg->kmem, name);
+ return res_counter_read_u64(&memcg->kmem, name);
break;
default:
BUG();
}
-
- return val;
}
#ifdef CONFIG_MEMCG_KMEM
@@ -5440,7 +5385,10 @@ static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
if (!t)
goto unlock;
- usage = mem_cgroup_usage(memcg, swap);
+ if (!swap)
+ usage = res_counter_read_u64(&memcg->res, RES_USAGE);
+ else
+ usage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
/*
* current_threshold points to threshold just below or equal to usage.
@@ -5532,15 +5480,15 @@ static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
mutex_lock(&memcg->thresholds_lock);
- if (type == _MEM)
+ if (type == _MEM) {
thresholds = &memcg->thresholds;
- else if (type == _MEMSWAP)
+ usage = res_counter_read_u64(&memcg->res, RES_USAGE);
+ } else if (type == _MEMSWAP) {
thresholds = &memcg->memsw_thresholds;
- else
+ usage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
+ } else
BUG();
- usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
-
/* Check if a threshold crossed before adding a new one */
if (thresholds->primary)
__mem_cgroup_threshold(memcg, type == _MEMSWAP);
@@ -5620,18 +5568,19 @@ static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
int i, j, size;
mutex_lock(&memcg->thresholds_lock);
- if (type == _MEM)
+
+ if (type == _MEM) {
thresholds = &memcg->thresholds;
- else if (type == _MEMSWAP)
+ usage = res_counter_read_u64(&memcg->res, RES_USAGE);
+ } else if (type == _MEMSWAP) {
thresholds = &memcg->memsw_thresholds;
- else
+ usage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
+ } else
BUG();
if (!thresholds->primary)
goto unlock;
- usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
-
/* Check if a threshold crossed before removing */
__mem_cgroup_threshold(memcg, type == _MEMSWAP);
@@ -6390,9 +6339,9 @@ mem_cgroup_css_online(struct cgroup_subsys_state *css)
* core guarantees its existence.
*/
} else {
- res_counter_init(&memcg->res, NULL);
- res_counter_init(&memcg->memsw, NULL);
- res_counter_init(&memcg->kmem, NULL);
+ res_counter_init(&memcg->res, &root_mem_cgroup->res);
+ res_counter_init(&memcg->memsw, &root_mem_cgroup->memsw);
+ res_counter_init(&memcg->kmem, &root_mem_cgroup->kmem);
/*
* Deeper hierachy with use_hierarchy == false doesn't make
* much sense so let cgroup subsystem know about this
@@ -6510,11 +6459,6 @@ static int mem_cgroup_do_precharge(unsigned long count)
int batch_count = PRECHARGE_COUNT_AT_ONCE;
struct mem_cgroup *memcg = mc.to;
- if (mem_cgroup_is_root(memcg)) {
- mc.precharge += count;
- /* we don't need css_get for root */
- return ret;
- }
/* try to charge at once */
if (count > 1) {
struct res_counter *dummy;
@@ -6825,21 +6769,18 @@ static void __mem_cgroup_clear_mc(void)
/* we must fixup refcnts and charges */
if (mc.moved_swap) {
/* uncharge swap account from the old cgroup */
- if (!mem_cgroup_is_root(mc.from))
- res_counter_uncharge(&mc.from->memsw,
- PAGE_SIZE * mc.moved_swap);
+ res_counter_uncharge(&mc.from->memsw,
+ PAGE_SIZE * mc.moved_swap);
for (i = 0; i < mc.moved_swap; i++)
css_put(&mc.from->css);
- if (!mem_cgroup_is_root(mc.to)) {
- /*
- * we charged both to->res and to->memsw, so we should
- * uncharge to->res.
- */
- res_counter_uncharge(&mc.to->res,
- PAGE_SIZE * mc.moved_swap);
- }
+ /*
+ * we charged both to->res and to->memsw, so we should
+ * uncharge to->res.
+ */
+ res_counter_uncharge(&mc.to->res,
+ PAGE_SIZE * mc.moved_swap);
/* we've already done css_get(mc.to) */
mc.moved_swap = 0;
}
--
1.9.2
--
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